The invention relates to reaction products of ethoxylated alcohols, and most particularly relates, in one non-limiting embodiment, to coupled alcohol ethoxylates for improving the thermal properties of compositions in which they are included.
The reaction of isocyanates with hydroxyl-containing materials is well known and widely practiced. The most common use of this reaction is for the production of polyurethanes by reaction of various polyols with diisocyanates. For this purpose, primarily toluene diisocyanate (TDI) or methylenediphenyl diisocyanate (MDI) or a combination of the two has been used with a broad range of polyols. More recently, certain aliphatic or alicyclic diisocyanates (e.g., cyclohexane diisocyanate or isophorone diisocyanate) have been used in making certain polyurethanes, especially for coatings. Such aliphatic diisocyanates, either alone or in combination with the aforementioned aromatic diisocyanates, are used because they provide added flexibility to the finished polyurethane coating.
It is also well known that, aside from reacting with alcohols and polyols, isocyanates will react with other materials containing groups possessing a replaceable hydrogen atom. Such materials include primary and secondary amines, hydroxylamines, carboxylic acids, phenols and water. With water, the initial reaction converts the isocyanate to a carbamic acid, which, due to the heat generated, loses carbon dioxide to give a primary amine. The amine, in turn reacts with another isocyanate to form a urea molecule, which may further react to form a biuret. In this fashion, one mole of water will consume two or more equivalents of isocyanate while releasing a mole of CO2. In producing certain foamed polyurethane products, excess diisocyanate is incorporated along with water to purposely generate some CO2, which acts as a blowing agent. In these cases, the urea/biuret species form part of the polymer structure.
In the toner industry that manufactures powders for use in xerographic reproduction, accumulation of production waste classified as ultra fines has become a major concern. Thus, it would be desirable if some method or component that would improve the homogeneity or compatibility of the various toner components could be devised. It would also be advantageous to improve the compatibility of the various components of powder coatings, and to improve the adhesion of polishes and waxes to the article treated.
An object of the invention is to provide a compatibilizing component that would improve the homogeneity of powdered toners and powdered coatings.
Other objects of the invention include providing a component that would improve the adhesion of polish or wax to the article to which it is applied.
Another object of the invention is to provide a compatibilizing component that is readily manufactured.
In carrying out these and other objects of the invention, there is provided, in one form, a coupled alcohol ethoxylate produced by reacting an ethoxylated derivative of a saturated linear alcohol with a diisocyanate. In one non-limiting embodiment, the linear alcohol may have a carbon atom chain length ranging from about 20 to about 70.
In another embodiment of the invention, there is provided a toner composition having resin particles, pigment particles, wax particles, and an amount of a compatibilizing component effective to improve the homogeneity of the composition, where the compatibilizing component is a coupled alcohol ethoxylate.
In yet another embodiment of the invention, there is provided a powder coating that includes resin particles, pigment particles, wax particles, extender particles, and an amount of a compatibilizing component effective to improve the homogeneity of the composition, where the compatibilizing component is a coupled alcohol ethoxylate.
In still another embodiment of the invention, there is provided a polish (wax) for an article comprising an amount of a coupled alcohol ethoxylate effective improve adhesion.
It has been discovered that coupled alcohol ethoxylates are useful dispersion aids for toners and powder coatings and the like. Indeed, the inventors in their study focusing on the advantages of inventive compounds in dispersing wax in toner resin came to a number of important conclusions:
Compatibilizers will assist in the production process to yield a more homogenous mixture of small wax domains.
A homogenous mix of small wax domains should increase production efficiency, while decreasing generation of waste material.
The toner waste material should experience a decrease in free wax, which would encourage the recycling of the materialxe2x80x94thereby greatly reducing storage and disposal concerns.
Image quality will be improved by discouraging drum filming caused by the presence of free wax.
A better wax dispersion in toners and powder coatings will also increase the life of consumable machine parts.
The coupled alcohol ethoxylates of the present invention relate to toners as a dispersion aid or compatibilizer of the various ingredients within the binder resin or melt blend. The toner of the present invention can be obtained through the addition of various pigments, charge control agents, magnetic powders and other optional components to the binder resin. The melt is subsequently dispersed through the use of a super mixer, Danbury mixer, roll mill, kneader or extruder, as non-limiting examples. Rough pulverization of the cooled melt is carried out through the use of a cutter mill, hammer mill or similar process; fine pulverization with a jet mill, as non-limiting examples; classifying with a wind power classifier or other classifier known in the art. Normally, a surface treatment of the resulting product with various additives is included as a finishing step of the process.
The dispersing of the ingredients within the binder resin is often thought to be the most critical part of toner production. A good dispersion used with a robust formulation yields excellent image density and background without sacrificing the normal increase in toner consumption. The dispersion is also useful in enabling the producer to utilize the recycle, or fine material, often generated as a by-product of the operation. Adequate dispersion of charge control agents, and iron oxides will help to stabilize the charge of the toner particles thereby increasing the developer life.
The resin particles may include, but are not necessarily limited to, a styrene-butadiene, styrene acrylate, a styrene methacrylate, a polyester, an epoxy, an acrylic or mixtures thereof. A preferred resin selection includes, but is not necessarily limited to, a polymer such as a polyester, copolyester, and mixtures thereof, including reactively extruded polyesters. In another non-limiting embodiment of the invention, the resin particles comprise polyester/xcex2-hydroxyalkylamide powders. A particularly preferred form of xcex2-hydroxyalkylamide are PRIMID(copyright) powders available from EMS-Chemie AG. In one non-limiting embodiment, PRIMID XL-552 (bis-N,N-dihydroxyethyladipamide) is preferred although other xcex2-hydroxyalkylamides are suitable.
Representative examples of the above-mentioned pigment include, but are not necessarily limited to, carbon black, nigrosine, aniline blue, charcoal blue, chromium yellow, ultramarine blue, dupone oil red, quinine yellow, Methylene Blue Chloride, phthalocyanine blue, malachite green ocsalate, lamp black, Rose Bengal mixture thereof and the like. The ratio of the pigments is such that the corresponding image is visibly and measurably sufficient.
Representative examples of the magnetic powder include, but are not necessarily limited to, metals having strong magnetic properties, such as ferrites, magnetite, iron, cobalt, nickel, alloys thereof and compounds comprising these elements; and alloys which do not comprise strong magnetic elements but show strong magnetic properties when preferable heat treatment is performed. Mixtures of these magnetic powders are also acceptable. These magnetic powders are dispersed with an average weight of 20 to 70 parts to 100 parts of the binder resin, preferably between 40 and 60 parts by weight. The two-component developer can be obtained through mixing of the toner with carriers such as ferrite or iron powders. The toner utilized in a two-component system typically contains magnetic powders that are dispersed with an average weight of 0.1 to 5 parts to 100 parts of the binder resin.
The present invention relates to the modification of certain materials to increase their softening temperatures, glass transition temperature (Tg) and other thermal properties while retaining their basic compatibilities with other materials. Specifically, UNITHOX(copyright) Ethoxylated Alcohols (available from Baker Petrolite) are modified by reaction with toluene diisocyanate (TDI) or methylenediphenyl diisocyanate (MDI) or mixtures of the two, to couple the terminal hydroxyls of two poly(oxyethylene) groups via formation of a bridging aromatic diurethane linkage. Without wishing to be bound by any single theory, it is believed that such bridging results in a xe2x80x9chairpinxe2x80x9d configuration in which the aromatic group is at the central curve, poly(oxyethylene) groups trail down each prong and fully linear, saturated hydrocarbon chains, ranging from 20 to 70 or more carbon atoms each, complete the prongs. Such a configuration will give better packing of molecules when compared with the non-coupled UNITHOX resulting in a more stable, more crystalline material.
In one non-limiting embodiment of the invention, the equivalent ratio of diisocyanate per hydroxyl equivalent in the ethoxylated alcohol ranges from about 0.2:1 to about 1.5:1. As noted, it is generally expected that one mole of diisocyanate reacts with 2 moles of ethoxylated alcohol. However, as will be shown, different reactant proportions give somewhat different results. The reaction of the diisocyanate may be catalyzed with any conventional catalyst, including, but not necessarily limited to, tertiary amines, tin compounds, etc.
More specifically, the ethoxylated alcohols may contain saturated hydrocarbon chains of from about 20 to 70 carbon atoms, preferably from about 30 to 50 carbon atoms. The alcohols may be ethoxylated with anywhere from about 4 to about 90 moles of ethylene oxide per mole of alcohol, preferably from about 10 to about 30 moles of ethylene oxide per mole of alcohol. The ethoxylation may be conducted by any known means in the art.
It is known that certain UNITHOX products are useful as dispersing agents for pigments in water as well as for dispersing hydrocarbon waxes (e.g., polyethylene, paraffin, microcrystalline waxes) in water. Also, certain UNITHOX products exhibit compatibility with various synthetic resins. The above-described modification does not significantly alter these properties and compatibilities. The proportion of coupled alcohol ethoxylates in a toner composition may range from about 0.05 to about 20 wt. %, based on the total toner composition, preferably from about 1.0 to about 10.0 wt. %, and most preferably from about 1.5 to about 5.0 wt. %.
An unmodified UNITHOX product may be used to disperse pigment, wax and other additives in a polyester, copolyester or reactively extruded polyester that is used as a binder resin for a toner. However, when used at the required level, sometimes the resulting toner particles tend to block under conditions of higher temperature and humidity that are frequently encountered especially during the summer months. Coupling these ethoxylates as described above will greatly reduce this blocking without significantly impacting their dispersing properties. This reduction in blocking is due not only to the increased thermal properties of the coupled ethoxylates, but also to a decrease in their hygroscopicity and an increase in their hardness. A decrease of the hygroscopic nature of the commercially available alcohol ethoxylate product is expected to help avoid subsequent storage/stability concerns of the finished toner powder. Additionally, an increase in hardness of the commercially available alcohol ethoxylate product is expected to improve the traditional production of toner.
Similar proportions of coupled ethoxylated alcohol may be used in powder coating compositions. Such powder coating compositions typically include resin particles, wax particles, pigment particles, extender particles, and optionally a degassing agent. The degassing agent may be present in an amount from about 0.05 to about 20 wt. %. The wax particles in powder coatings may be reactive or nonreactive with the other components in the system. Similarly, it is expected that the coupled ethoxylated alcohols of this invention will find utility in polishes and waxes for articles such as automobiles, glass, ceramics, etc. to improve the adhesion of the wax or polish thereto. Within the scope of this invention, when the term xe2x80x9cpolishxe2x80x9d is used, it is intended to include the term wax, where wax is used in this context of an automotive wax, glass polish, ceramic polish or wax or polish for another article, in contrast to the wax particles of the toner or powder compositions.
The inventive compatibilizing components are also expected to find utility as dispersing agents for various pigments and hydrocarbon waxes in water-based systems.
The invention will be further discussed with respect to the following Examples that are presented not to limit the invention but simply to further illustrate it.